1. Field of the Invention
The present invention relates to a film prewinder for cameras which includes a fail-safe system for automatically prewinding a film again or resuming a film prewinding mode without having to open the camera back cover in the event of a film prewinding failure.
2. Discussion of the Background
There is known a camera with a film prewinding mechanism which is powered by a battery assocated with the camera. When a film cartridge is loaded in the camera, the film prewinding mechanism pulls substantially all of the film continuously out of the cartridge. Then, the film is rewound back one frame at a time into the cassette as the film frames are successively exposed.
When the film prewinding mechanism is in operation, it must to be energized continuously by the battery since the relatively long film must be pulled out of the cartridge without interruption. However, if the battery has already been consumed or is not powerful enough due for example to a low temperature, the film prewinding mechanism may be stopped while the film is being prewound. Where the camera is controlled by a sequence control circuit incorporated therein, the operation sequence is brought to an end upon interruption of the film prewinding process due to a power failure. Once this sequence interruption occurs, the sequence control circuit does not start the film prewinding mode again even if the battery restores its desired power supply capability. For restarting the sequence process, therefore, it is necessary to open the camera back cover, remove the cartridge, replace the battery with a new battery to initialize the sequence control circuit, and then load the cartridge again to start prewinding the film once more.